But Obama hasn't won every Hollywood star's support. Ralph Nader, the habitual presidential candidate (and Barack Obama trash talker), claims a few too. They'll be joining him in Denver on Aug. 27 for a rally that Nader's campaign hopes will upstage -- or at least share a stage with -- the Democrats' fanfare.

Val Kilmer and Sean Penn will be the biggest personalities at the "Open the Debates" rally, which Nader is hosting at the University of Denver Magness Arena with his running mate, Matt Gonzales. Musicians Nellie McKay, Ike Reilly, Tom Morello (of Rage Against the Machine) and Jello Biafra (of the Dead Kennedys) will also appear.

OK, so it may be a kind of a B-list batch compared with Obama's all-star cast. But Nader spokesman Chris Driscoll promises a crowd of 5,000 to 7,000, as well as downright "electric" energy.

The rally will call for Nader -- and any other viable third-party candidate -- to be included in the upcoming presidential debates. (Libertarian candidate Bob Barrhas been clamoring for the same privilege -- but without Hollywood's help.)

In November, Nader will be on the ballot in 45 states, according to the campaign. In the latest CNN poll, 6 percent of respondents said they would vote for the Nader/Gonzalez ticket.

Nader's campaign is planning a second "Super Rally" in Minneapolis on Sept. 4 at Orchestra Hall during the week of the Republican National Convention, where he'll try to snag votes from the fringes of the GOP.